The function of n-and-n is to reduce n by 1. For example, after the original n is 5, n- or -n becomes 4.

The difference between them is that:

N- The value of this expression is the value before subtracting n, for example:

int n = 5；

int a = n-； //At this time, the value of a is 5.

N- The value of this expression is the value after subtracting n, for example:

int n = 5；

int a =-n； //At this time, the value of a is 4.

For example:

n = 10；

k = 10 * n-+3；

Then after the end, k= 103, n=9.

-n In the expression, subtract n from n first, and then take the value of n for operation;

For example:

n = 10；

k =-n * 10+3；

Then after the end, k=93, n=9.

If it is a separate statement-n; Then use n-; There is no difference at all.

Extended data:

C language is a general computer programming language, which is widely used in the bottom development. The design goal of C language is to provide a programming language that can compile and process low-level memory in a simple way, generate a small amount of machine code and run without any support of running environment.

Although C language provides many low-level processing functions, it still maintains good cross-platform characteristics. C language programs written in standard specifications can be compiled on many computer platforms, even including some embedded processors (single chip microcomputer or MCU) and supercomputers.

In 1980s, in order to avoid the differences of C language grammars used by different developers, the American National Bureau of Standards formulated a complete set of American national standard grammars for C language, called ANSI C, as the original standard of C language. [1] At present, the standard C 1 1 issued by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) on February 8, 2000 is the third official standard of C language, and it is also the latest standard of C language, which better supports it.

C language is a process-oriented computer programming language, which is different from object-oriented programming languages such as C++ and Java.

Its compilers mainly include Clang, GCC, WIN-TC, SUBLIME, MSVC, Turbo C and so on.